This invention relates generally to electrophotographic printing, and more particularly, concerns cleaning imaging (i.e. photoreceptive, photoconductive, etc.) and bias transfer roll (BTR) surfaces using air velocity.
High velocity air streams have been used to clean photoreceptors in the past. Although several attempts have been made to clean photoreceptors and bias transfer rolls (BTRs), none of these attempts appear to be known to have been used in copiers. These devices, photoreceptors and BTRs, have used air knives to create a high velocity air stream to clean their surfaces. Such devices can consist of a plate, closely spaced to the surface to be cleaned, with narrow slots cut into it. A vacuum is applied behind the plate to cause air to flow through the slots and create a high velocity airstream across the surface being cleaned. The high velocity air flow disturbs the surface boundary layer allowing removal of particles adhered to the surface. The problems with this approach are in the manufacture of the device and the power required to create the vacuum. The tolerances for the cleaner and the surface to be cleaned must be held closely. The orifice slot width must be uniform along its length to maintain uniform air velocities and therefore cleaning. The spacing between the plate and surface to be cleaned must also be uniform for the same reasons. This requires the plate and cleaning surface to be straight, flat and well aligned. If the surface to be cleaned is a roll, the runout of the roll and the parallelism of the roll axis to the slot axis is also important. Because of the close spacing of the cleaning plate to the surface to be cleaned and the narrow orifice slot, the resistance of the system to air flow is very high. As a result of this high resistance to air flow, a considerable air flow is required to generate the required cleaning air velocities needed for the narrow orifice slot to clean the surface. The requirements of high pressure and air flow result in a high power usage for the system and the possibility of a noise problem.
The following disclosures may be relevant to various aspects of the present invention and may be briefly summarized as follows:
U.S. Pat. No. 3,766,593 to Becker et al. discloses an apparatus for cleaning residual particulate material. The apparatus comprises stationary brushes and a brush housing. The stationary brushes are for cleaning residual toner from the surface of a photoconductor. The brush housing is designed so that air flow is at a maximum. A vacuum means is included in the brush housing.
U.S. Pat. No. 3,932,910 to Shimoda discloses a cleaning apparatus for an electrophotographic copying device comprising: (1) a cleaning brush; (2) a casing for the brush wherein the brush is positioned adjacent a first opening so as to contact a work surface; and (3) a means for suction of particles. The cleaning brush is provided for cleaning off particles from a photosensitive surface. A plate which surrounds part of the cleaning brush is provided for introducing air into the casing.